1. ¹Kirin Brewery Co., Ltd, Research Laboratory for Brewing, 1-17-1 Namamugi Tsurumi-ku, Yokohama 230-8628, Japan
2. ²East Malling Research, Department of Hop Research, Wye, Ashford, Kent TN25 5AH, England
3. ³Center for Plant Biotechnology and Breeding, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia
4. ⁴Laboratory of Plant Biotechnology – ICAT, Edificio ICAT, Campo Grande 1749-016, Lisbon, Portugal
5. ⁵Bayer, Landesanstalt für Landwirtschaft, Institut für Pflanzenbau und Pflanzenzuechtung, Arbeitsbereich Hopfen, Huell 5 1/3, D-85283 Wolnzach, Germany
6. ⁶Hop Research Institute Co., Ltd, Kadaská 2525, 43846 atec, Czech Republic

Correspondence: A Murakami, Current address: Kirin Brewery Co., Ltd, Shiga, 1600 Binmanji, Tagacho Inukamigun, Shiga 522-0342, Japan. E-mail: m-atsushi@kirin.co.jp

Received 3 July 2005; Accepted 10 April 2006; Published online 10 May 2006.

Abstract

We have analysed wild hops collected widely from the Northern Hemisphere, assessing the genetic diversity and the geographical distribution of haplotypes, to investigate the evolution and phylogeny of hops, Humulus lupulus. The haplotypes were characterized by the nuclear ribosomal DNA spacer region (length and DNA sequence) and chloroplast DNA noncoding regions (DNA sequences). The results indicated that primary divergence into European (including Caucasus and Altai hops), and Asian-North American types, was 1.050.28 to 1.270.30 million years ago. Although an Eastern boundary for European nuclear haplotype distribution was unclear due to the ambiguous origin of Northern Chinese samples, the European hop group showed a wide geographical distribution across Eurasia from the Altai region to Portugal. The low genetic variation in this group suggested rapid and recent expansion. The North American hop group showed high diversity, and is considered to include hops that have migrated from Asia. Japanese and Chinese hops were identified as genetically distinct. This study has shown that wild hops in each growing region are genetically differentiated with considerable genetic diversity. It gives insights into the evolution and domestication of hops that are discussed.